Chemical Analysis of the Green Shell of (he Walimt. 449 



gaffed from this same extract by the acklitiou of sulphuric 

 acid, even when assisted by heat ; it dot- s not therefore con- 

 tain any acetic acid. 



From what has been said, it appears, that in the rind of 

 the wahiut, as well as in many other herl)aceous plants, 

 there exists a matter held in solution in their fluids, the ra- 

 dical of which is hydi'o-carbon, more or less easily decom- 

 posable by the simple contact of air, wliich thus favours the 

 production of water in rendering the carbon predominant. 

 It will readilv be conceived, that it is irnpossil)le to have a 

 very exact notion of a matter so little permanent. Neverthe- 

 lcs6, we perceive that it is scarcely coloured in the vessels 

 of the plant, and that the action of air or caloric changes it 

 greatly, causing it to jiass by deorces into the state of ex- 

 tractive; another principle but badly dcflnrd, unstable in 

 its elements, appearina" rather to be the result of a deconi- 

 }>osition, than a true product of living nature*. 



The juice of i!ie walnut sb.cll, analysed by diiTercnt re- 

 agents, afibrded the .following results. 



jt strongly reddened the infusion of turnsole. A solution 

 of gelatin produced from it a sligiu precipitate, which must 

 be owing to the tannin it contains. The sulphate of iron 

 strikes so deep a green colour with this juice, that the li- 

 (p'.or appear-^ black : it afforded no precipitate, even by time, 

 on account of the uncombined acid in the mixture, which 

 is capable of giving a fine gray colour to wool and silk. 

 Oxalate of ammonia indicated llse presence of lime in this 

 juice. Nitrate of barvtes did not produce any sulphate. 

 'J'he nitrate of silver acts upon the juice, so as to detect the 

 pi-csence of the hydru-carbou radical, for it produced from 

 It an abundant precipitate which speedily became coloured, 

 and put on a metallic brilliant ajipearancc by the reaction 

 of the veiretable matter upon the oxygen of tlie oxide of sil- 

 ver : this precipitate was only partly soluble in the nitric 

 acid^ and lel'i a coaly residue. Alkalies colour the walnut 



* Having occasion to cxaraiiiesonie extract of the Rhus to-ncadendron prc- 

 p<;rcd a lew years ago, I made ilic iollnwing cxperinicxit. ) atiplied sonic of 

 it upon the skin cf an aiiiina!, and caused iiim to swallow some large dose* 

 (/f it, without h.is experiencinjif any untoward etTec's ; wliile.S'idrop of juice 

 from tlie stalk of tlie plniit occasioned a violent inflamiEaitan upon the skin, 

 tiirniiiiatinij in an ulcer. ']"lie principles of [ilants tlieretbre auproachitig to 

 the state ofextiact, undergo an aJlerat'on which cor.tinitally increases with 

 time, and which must considerably vary their action upon the animal a-oono- 

 iny. Apothecaries might to a certain df;rree prevent tins alteration, by in- 

 closing the extracts in a state oi perltcL dryiuss in well-siopped vcasels ; for 

 ilic Iiumidity v/liich lliey contain, or fend-to ab.-orh, contributes no less than 

 the contact of air to destroy llie weak equilibrium of some ol their elements.- 



Vol. 3S. Mo. 16'1. Dei. Itill. Ff juici* 



